1. Field of the Invention
This invention relates to bleaching compositions. More particularly, the invention encompasses improved bleaching compositions and a process for activating peroxygen bleaching agents not only to bleach fabrics, but also to inhibit dye transfer during the wash cycle of a laundering procedure.
It is known that peroxygen bleaches such as diperoxyisophthalic acid, m-chloroperbenzoic acid, sodium perborate and the like, can be used in washing and beaching baths to aid in the cleansing and bleaching of fabrics. In general, however, optimum cleaning and bleaching with peroxygen bleaches occurs at temperatures near or above the boiling point of water, especially when sodium perborate type bleaches are used. When such peroxygen bleaches are employed in the wash bath at temperatures below about 90.degree. C, sub-optimal cleansing and bleaching occurs because the release of active oxygen does not proceed with sufficient rapidity. Thus, there is a continuing search for compositions and methods to bleach and inhibit dye transfer of textiles and fabrics effectively at temperatures below 90.degree. C, e.g., in the 30.degree. C to 80.degree. C temperature range typical of modern washing machines used in the United States.
Peroxygen bleaches are especially desirable for use on fabrics due to their marked superiority in providing improved hand feel, improved absorbency, permanency of whiteness, color safety, and low rate of dye transfer in colored fabrics, in comparison with the harsh hypochlorite bleaches. Despite their many potential advantages, sodium perborate type peroxygen bleaches suffer from the disadvantage that optimum realization of their beneficial properties can only be achieved at unusually high laundry bath temperatures. Thus, it is essential to incorporate an activator in compositions containing the peroxygen bleaches to catalyze their bleaching and dye transfer inhibition action, thereby providing effective bleaching at somewhat lower temperatures.
It has now surprisingly been found that the use of certain di-ketones in combination with certain organic peroxygen bleaching agents provides a significant improvement in the cleansing and bleaching of fabrics. Moreover, the di-ketone/peroxygen bleaches herein serve to inhibit dye transfer between colored fabrics during a laundering process at normal wash temperatures.
2. The Prior Art
The use of chlorine and active oxygen bleaches to enhance cleansing and to remove stains from fabrics during a laundering operation is well-known.
U.S. Pat. No. 3,882,114, Montgomery, Bleaching Process and Compositions Therefor, July 4, 1974, describes a dry bleach composition containing a peroxyacid bleaching agent, an aldehyde- or ketone-producing activator, and a buffering agent. Aliphatic, aromatic, or cyclic ketones which can be either saturated, unsaturated, substituted or unsubstituted are disclosed. The di-ketones used herein are superior to those activators and dye transfer inhibitors disclosed in the '114 patent.
U.S. Pat. No. 3,775,322, Heins, et al., Method of Activating Per-Compounds and Solid Activated Per-Compound Compositions, Nov. 27, 1973, relates to the activation of solid inorganic per-compounds such as the perborates utilizing acetylated glycolurils and diacylated 2,5-diketopiperazines.
U.S. Pat. No. 3,775,333, Loffelman, et al., N-acyl Azolinones as Peroxygen Bleach Activators, November 27, 1973, teaches the activation of peroxygen bleaches using N-acyl azolinone type compounds. The activated bleach compositions are described as effective at low temperatures (e.g. 50.degree.-.degree. C).
Other prior art bleaching compositions have employed various types of such activator compounds including esters, carboxylic acid anhydrides, quaternary ammonium salts and carboxylic acid salts, among others. (See; Popkin, U.S. Pat. No. 1,940,768, Dec. 26, 1973; Baevsky, U.S. Pat. No. 3,061,550, Oct. 30, 1962; MacKellar, et al., U.S. Pat. No. 3,338,839, Aug. 29, 1967; Woods, U.S. Pat. No. 3,532,634, Oct. 6, 1970; and Staher, U.S. Pat. No. 3,556,711, Jan. 19, 1971. U.S. Pat. Nos. 3,739,673 and 3,749,674, Jones and Nicol, each relate to activated bleaches and their use to combat dye transfer.) While certain of these activators are presumably effective, there is a continuing need for activators other than those presently employed in the art so that better bleaching performance and dye transfer inhibition can be obtained with peroxygen bleaches.
The bleaching compositions and processes herein can be used in several ways to solve cleaning and laundering problems encountered in the home. The bleaches can be used to remove stains from fabrics and hard surfaces. The bleaches can also be formulated in combination with detersive surfactants, builders, and the like, to provide fully-formulated bleaching cleansers and laundry detergents. Moreover, the compositions herein help combat one of the most persistent and troublesome problems arising during a fabric laundering operation, i.e., the release of dyes into laundering solutions and transfer of the dyes to other fabrics being washed. Heretofore, there has been no reliable way to combat the problem of dye transfer, other than by mechanically sorting the fabrics to partition them into dark and light shades for separate laundering.
In light of the foregoing considerations concerning direct bleaching and dye transfer in laundering, it is an object of the instant invention to provide improved methods for enhancing the activity of peroxygen bleaches.
It is a further object of this invention to provide improved concentrated bleaching compositions for use alone, or in conjunction with other conventional laundering agents.
It is yet another object herein to provide compositions which prevent visible dye transfer onto fabrics.
These and other objects are obtained herein as will be seen from the following disclosure.